3 ohm spark plug caps?

[Manfred]

The spec sheet on the Accel web site states they use 8.8mm wires - I think you are correct about their make-up. Accel states their wires are rated at 3 ohms for the kit I bought: http://prestoliteperformance.com/Portal ... S_0001.pdf

[Manfred]

I just rec'd an answer from the folk at Accel: "As long as the wires you have are designed for your type of ignition system you should be fine." I will stay with my 2-year old caps and wires. She started up fine this morning and runs smooth. Can run faster and jump higher!

[chasbmw]

Duane,

Most of the microprocessor controlled after market ignition systems for airheads, specify the use of 5000 OHM resistor plug caps. I think that this is to prevent any 'noise' from upsetting or destroying the electronics.

See the websites for Silent Hektik and Sachse.

For the Boyer ignitions only the Microdigital requires resistor plug caps, the basic Mk 111 does not.

I'm not sure if resistor plug caps are needed for the BMW electronically triggered ignition.

Charles

[Duane Ausherman]

chasbmw, thanks for the info on modern ignition requirements. While my background is electronics, I have no knowledge of the modern ignition systems.

The resistor will take the simple square wave and round off the sharp corners. A square wave is full of harmonics. Harmonics are what we call "noise" and are generally not nice. In the olden days we mostly didn't care about the noise. Noise might cause interference in radios of cars, but who cares? Now that some bikes carry an AM radio and the microprocessor is sensitive to very small amounts of EMP, the bike's ignition system must not generate a signal that is its own death.

[Manfred]

I've had the Accel coil in place (with my NGK wires and caps) for a few tanks of fuel now. The bike starts very quickly, runs smooooooooooth in all RPMs, and takes me some 20 - 25 miles further on a tank of fuel. Mucho more smiles per mile and more of those per tank - who could ask for anything more?

[John Falconer]

Thank you Duane. Five ohms - no, never heard of such a thing. If they are, in fact 3K ohm - I'd probably go ahead although I like the NGK caps very much myself and find the metal BMW OEM caps too unreliable.

[Duane Ausherman]

The original metal caps were very unreliable in San Francisco due to the high humidity from the fog. I replaced all of them with those small cheap Sparkys and they worked very well. They had no resister.

If the resister caps were only for radio noise, then they would not cause a failure of the electronic ignition, which I hear that they do. So, it is something else besides radio noise. I really can't imagine because adding 3 k Ohms to a ignition line is nothing compared to the resistance of air.